<template>
  <div class="TableHeaderTest">
     <el-tree
  :data="data"
  show-checkbox
  node-key="id"
  :default-expanded-keys="[1]"
  :props="defaultProps">
</el-tree>

  </div>
</template>
<script>
export default {
  methods: {},

  data() {
    return {
      expandedKeys:[],
       data: [{
          id:1,
          label: '一级 1',
          children: [{
            id:2,
            label: '二级 1-1',
            children: [{
              id:3,
              label: '三级 1-1-1'
            }]
          }]
        }, ],
        defaultProps: {
          children: 'children',
          label: 'label'
        }
    }
  },
  mouted(){
     //this.expandedKeys.push(1)
  },
  methods:{
      
  }
};
</script>

<style>
</style>